By Julie Steenhuysen CHICAGO (Reuters) – Scientists have been puzzling for years over why some people survive Ebola while many others perish. Researchers at the University of Washington in Seattle reported their findings on Thursday in the journal Science. Mice used in the study were generated from eight different strains of the animal and were bred to represent human genetic diversity. Symptoms in these genetically diverse mice ranged from mild weight loss to full, hemorrhagic fever, including internal bleeding, swollen spleens and changes in liver color and texture.